1. Field of the Invention
The present invention relates to an orthogonal two-axis moving apparatus which can move one end portion of an arm to an arbitrary position within a plane having two axes, i.e., one axis parallel to an extending direction of the arm and an axis perpendicular to the one arm.
2. Background Art
Conventionally, various orthogonal two-axis moving apparatuses are known, each of which can move one end portion of an arm to an arbitrary position within a plane having two axes, i.e., one axis parallel to an extending direction of the arm and an axis perpendicular to the one arm. For example, as shown in FIG. 29, a slide block a is slidably supported by first and second guide rods b and c which are perpendicular to each other. Two orthogonal ball screw shafts d and e extend through the slide block a in a threadably engaged state The first ball screw shaft d is rotated by a first driving motor f mounted on one end of the first guide rod b, and the second ball screw shaft e is rotated by a second driving motor c mounted on one end of the second guide rod c.
In the conventional orthogonal two-axis moving apparatus with the above structure, the slide block a can be moved to an arbitrary position in a plane including the first and second guide rods b and c by selectively driving the first and second motors f and g.
However, since the conventional orthogonal two-axis moving apparatus uses two expensive ball screw shafts, the apparatus becomes expensive, thus posing a problem in terms of a cost. Paying attention to the first driving motor f, a weight as a drive load of this motor is a sum of the weight of the slide block a and the weight of the second driving motor, and is considerably large. As a result, the first driving motor f must comprise a large capacity motor, and this also results in an increase in cost. In addition, the weight of a moving portion is increased, thus impairing movement performance.
Furthermore, demand has arisen for an inexpensive origin detection mechanism which can reliably detect origin positions of two axes, as starting points upon execution of movement control.